<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        html,
        body {
            height: 100%;
            width: 100%;
        }

        body {
            display: flex;
            flex-direction: column;
        }

        header {
            height: 100px;
            background-color: aquamarine;
        }

        main {
            flex: 1;
            background-color: yellow;
            display: flex;
        }


        footer {
            height: 100px;
            background-color: burlywood;
        }

        nav {
            width: 100px;
            background-color: blueviolet;
        }

        .side {
            width: 100px;
            background-color: violet;
        }

        .content {
            background-color: cornflowerblue;
            flex: 1;
        }

        .content:hover {
            flex-shrink: 4;
            transition: 5s;
        }
    </style>
</head>

<body>
    <!-- 需求:header和footer高度固定宽度自适应,main宽度高度都自适应,main中nav
        和side高度自适应宽度固定,content宽度和高度都自适应 -->
    <header></header>
    <main>
        <nav></nav>
        <div class="content"></div>
        <div class="side"></div>
    </main>
    <footer></footer>
</body>

</html>